1. Field of the Invention
The present invention relates to a mobile communication system, and more particularly, to a method and apparatus for managing an overhead channel of a base station in order to improve and stabilize the performance of a code division multiple access (CDMA) system.
2. Description of the Related Art
In a current CDMA mobile communication system, an overhead channel operating in a channel card of a base station transceiver subsystem (BTS), for example, a pilot channel, a synchronizing channel, a paging channel or an access channel, is previously assigned and thus fixedly operated. When paging a mobile station through a forward CDMA channel, the BTS pages a corresponding terminal through a previously assigned paging channel of a specific number (for example, 1). In a reverse CDMA channel, a fixedly assigned access channel of a specific number (for example, 1) is used for a connection between the mobile station and the BTS.
However, such a paging method has several disadvantages, as described below. In the forward CDMA channel, even though there is no overload across the BTS when paging the mobile station whose current position is accurately known, the load of the BTS increases when paging the mobile station whose current position is not accurately known. The reason why problems arise when paging the mobile station whose current position is not accurately known will now be described.
When paging the mobile station whose current position is not accurately known, a primary paging operation is conducted in a cell by the BTS and a secondary paging operation is conducted in a zone consisting of several BTSs or by the unit of LAI (Location Area Identification). If the position of the mobile station is not accurately known even by the secondary paging operation, a tertiary paging signal is broadcast by the unit of MSC (Mobile Switching Center).
The overload associated with the location of a subscriber results in significant overhead traffic in the BTS and, in extreme cases, may bring the system down. Moreover, even in the reverse CDMA channel, a large quantity of traffic may be generated due to several factors including: an increase in origination performed through the access channel by the mobile station; responses to the paging of the BTS; and an increase in the number of registrations. As this overload is applied to the limited access channel, a connection between the mobile terminal and the BTS may become unstable.
It is an object of the present invention to provide a method and apparatus for managing an overhead channel of a BTS so as to improve and stabilize the performance of a mobile communication system.
It is another object of the present invention to provide a method and apparatus for determining the capacity of an overhead channel by previously predicting a load between a forward link and a reverse link.
It is still another object of the present invention to provide a method and apparatus for dynamically assigning radio resources by previously predicting an overload of an overhead channel which may be generated during an occurrence of urgent circumstances.
In accordance with one aspect of the present invention, a method for managing an overhead channel of a base station in a mobile communication system includes the steps of: calculating a load of the base station and assigning a threshold value based on said calculated load; monitoring the actual load of the base station; if the actual load reaches the threshold value, transmitting an additional overhead channel assignment request message to a channel card interface processor and additionally assigning the overhead channel; and if the actual load is lowered, transmitting an overhead channel assignment release request message to the channel card interface processor and releasing the overhead channel.
In accordance with another aspect of the present invention, an apparatus for managing an overhead channel of a base station in a mobile communication system includes: a load calculation processor for calculating a load of the base station; a storage unit for storing resources related to the additional assignment of the overhead channel on the basis of the calculated load; an overhead channel controller for transmitting, if the actual load reaches a threshold value, an additional overhead channel assignment request message to a channel card interface processor and assigning an additional overhead channel, and transmitting, if the actual load is lowered, an overhead channel assignment release request message to the channel card interface processor and releasing the overhead channel.